Alright. That became quite a heated discussion, it seems. I suppose roddi came across differently than he intended; I think he is more of a coder type than the typical Arduino beginner - and thus he quickly became slightly frustrated with the IDE.
I just wanted to humbly voice my opinion that the Arduino IDE has a lot of potential in terms of future development (I believe that this is the modern way of putting it :-) ). I do see what most people said here: that the IDE is mostly addressed to the beginners - and non-hacker types. And it does do a great job in this - remembering how easy it has been for me to begin with Arduino in the last year (I had the board and IDE set up in maybe 20 minutes - in a break after lunch), this is amazing.
But there are lots of possible improvements. roddi has suggested technical improvements (on which I can not comment much). I would want to express a more simple suggestion: for me, it would be very helpful to simply implement cooperation with an external editor in a better way. The built-in editor does the trick for the beginning, but once the code gets larger (for me, it is already the case once i need to scroll), the IDE quickly starts to feel a bit long in the tooth... I now use an external editor in most such cases (much easier to set the font size, as just one example, or to use code folding, syntax highlighting, code completion...). Unfortunately, every time I have changed my code externally, and go back to Arduino for compiling/upload, the changes I made in the external editor are not reflected in the IDE. That could be much improved. I think that this would be a great improvement for many. (By the way, I use TextMate on my Mac as an external editor.)
Regarding the other suggestion roddi made: I recently became very confused about the best location of libraries. Since I started last year, I kept those in the Arduino package under /Applications on my Mac (in the "libraries" directory within that package). But in other places (at bildr.org) I had found that those should be stored under ~/Documents/Arduino (which is a location that goes against my feeling for how to organize files on my hard disk; to my feeling, anything in the /Documents directory of my home folder should only be hand-made documents that I have created (such as my own code), but not a library file I got from somewhere else; needless to say that this directory does not as of now exist on my hard disk :-D ). Anyway, the two locations suggested in different places do confuse me.
But the point of all of this is only to say that there is still a lot of improvements (and clarifications) that can be made to Arduino. And I look forward to see it evolve. And to discussing my two cents about the possible directions further. :-)